Grey (International usage) or Gray (primarily U.S. usage) describes various tints and shades in a range from Black to White, known as achromatic colors or neutral colors. In recent years, neutral colors had been reclassified to have low colorfulness and/or low chroma on a standard color wheel. Images which consist wholly of neutral colors are called monochrome, black-and-white, or grayscale images. The gray outputs of a color marking device are adjusted by a process called gray balancing. Gray balancing determines the output levels of each color of a color marking device needed to produce a neutral gray for color and grayscale images rendered or otherwise displayed on that device. This is based, in part, on a color profile of the device.
For many current color multi-function printing devices, gray balance along L* line is normally aim to a*=b*=0 under D50 or D65 illuminants which is defined by the International Commission on Illumination (CIE). However different customers have different gray balance preferences. For instance, some customers prefer warm neutral gray colors, while others prefer cold colors like metallic neutral color. Some customers claim the only gray balance preferred is black toner/ink color at a same L* under a same illuminant. Often, these user-preferred gray balance colors require that values for a* and b* are non-zero.
Accordingly, what is needed in this art are systems and methods for adjusting the neutral behavior of a color marking device to satisfy customer gray balance preferences in instances where values of a* and b* are not zero.